Analysis and design of networked control systems using the additive noise model methodology

Networked Control has emerged in recent years as a new and exciting area in systems science. The topic has many potential applications in diverse areas ranging from control of microrobots to biological and economic systems. The supporting theory is very rich and combines aspects of control, signal processing, telecommunications, and information theory. In this paper, we give a partial overview of recent developments in Networked Control with an emphasis on the additive noise model methodology. We also point to several open problems in this emerging area. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Detection and Mapping of Chimassorb 944FD Antioxidant Additive in Polyethylene Using TOF-SIMS

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) with either gallium or indium primary beams, has been evaluated as a method to measure the homogeneity of distribution of an antioxidant, Chimassorb 944FD (C944), in linear low-density polyethylene. The parent ion for the oligomer at m/z 599 is sufficiently weak that it could not be used to map the distribution of the additive throughout its most commonly used concentration range (0.1-0.5% (w/w)) in polyethylene. Instead, a mass fragment at m/z 58 was found to be sufficiently clear of interferences that it could be used as a surrogate for the parent ion. As a result, imaging of the antioxidant distribution was possible to concentrations as low as 0.1%, and a linear concentration calibration curve was obtained. The use of an indium primary beam improved the correlation coefficient for the quantitative measurement of C944; moreover, indium reduced the contribution from the polyethylene background at m/z 58 in relation to the total counts acquired.     

Quantitative assessment of surface-enhanced resonance Raman scattering for the analysis of dyes on colloidal silver

Factors that affect quantitative analysis by surface-enhanced resonance Raman scattering (SERRS) have been investigated using azobenzotriazol and reactive dyes. Preaggregation of the silver colloid was the most effective method to obtain repeatable and reproducible scattering. Aggregation by poly(l-lysine) or spermine provided better precision than aggregation by sodium chloride or nitric acid. Repeatable quantitative analysis was achieved with the azobenzotriazol dyes. A linear calibration graph was obtained over different concentration ranges below 10(-)(8) M, depending on the nature of the colloid. Calculations estimate that 10(-)(8) M is the concentration at which monolayer coverage of the dye on the silver colloid is achieved. Above 10(-)(8) M, there was only a minor increase in the scattering intensity from the azobenzotriazol dyes. In contrast, the reactive dyes did not give a response proportional to concentration over the range studied. The different responses obtained for the two types of dye are believed to be caused by differences in the nature of the interaction of the molecules with the silver surface. The conclusion reached is that control of the colloid preparation, aggregation process, and surface chemistry are essential for successful quantitative analysis of dyes on colloidal silver by SERRS.     

Line Harmonics of Converters with DC-Motor Loads

The line current and voltage harmonics generated by thyristor dc-motor drives, in particular with 3-phase 6-pulse dc converters, are analyzed. As industry continues to raise the power level of the converters, it is becoming more and more important to find techniques for calculating the current and voltage harmonics that avoid making the often unrealistic assumptions of the procedures used in the past. Yet these techniques must maintain, in as simple a form as possible, all the necessary curves and expressions for predicting them under the required conditions. A more accurate model of the line- current waveform is analyzed allowing for both the overlap angle and dc-current ripple, and the results are presented as a convenient set of graphs and also as a set of mathematical expressions for use on a programmable calculator. The calculated current harmonics are then used to derive the corresponding voltage harmonics toegther with their phase relationship. These voltage harmonics are then reconstructed into the relevant voltage waveform on a plotter.     

The effect of extended‐hours hemodialysis on outcomes: A systematic review and meta‐analysis

Extended‐hours hemodialysis is associated with improvements in quality of life (QoL) and mortality, but it may accelerate the loss of residual kidney function (RKF) and increase vascular access complications. Multiple established databases were systematically searched; randomized and non‐randomized studies were pooled separately. QoL outcomes were assessed using standardized mean difference (SMD), vascular access adverse events and mortality were assessed with relative risk ratios (RR). Four hundred seventy‐six patients from six trials were eligible. Data from randomized controlled trials (RCTs) could only be synthesized for vascular access adverse events and mortality, which demonstrated no significant change in vascular access adverse events (RR 1.25, 95% CI 0.88 to 1.77) or mortality (RR 2.29, 95% CI 0.60 to 8.71). Pooled data from non‐randomized trials demonstrated no significant difference in QoL (SF‐36 Physical Component Summary SMD 0.61, 95% CI ?0.10 to 1.31, SF‐36 Mental Component Summary SMD ?0.04, 95% CI ?0.61 to 0.54). RKF was assessed in one report which demonstrated a potential reduction over 12 months with extended‐hours hemodialysis. The majority of trials had high risk of bias. Extended‐hours hemodialysis was not associated with improved QoL or mortality, or increased vascular access events. Adequately powered RCTs are needed to fully assess extended‐hours hemodialysis.     

Key design issues for autostereoscopic 2‐D/3‐D displays

Abstract— Flat‐panel 2‐D/3‐D autostereoscopic displays are now being commercialized in a variety of applications, each with its own particular requirements. The autostereoscopic display designer has two key considerations to address in order to meet customer needs — the optical output of the display (defined by the output window structure) and the choice of optical components. Window structure determines 3‐D image resolution, achievable lateral and longitudinal viewing freedom, crosstalk, and 3‐D fringe contrast. Optical‐component selection determines the quality of the imaging of such windows, viewing distances, device ruggedness, thickness, and brightness. Trade‐offs in window design are described, and a comparison of the leading optical component technologies is given. Selection of Polarisation Activated Microlenses? architectures for LCD and OLED applications are described. The technology delivers significant advantages particularly for minimising nominal viewing distances in high pixel density panels and optimizing device ruggedness while maintaining display brightness.     

Experimental and simulated ultrasonic characterization of complex damage in fused silica

The growth of a laser-induced. surface damage site in a fused silica window was monitored by the ultrasonic pulse-echo technique. The laser damage was grown using 12-ns pulses of 1.053-μm wavelength light at a fluence of ~27 J/cm². The ultrasonic data were acquired after each pulse of the laser beam for 19 pulses. In addition, optical images of the surface and subsurface damage shape were recorded after each pulse of the laser. The ultrasonic signal amplitude exhibited variations with the damage size, which were attributed to the subsurface morphology of the damage site. A mechanism for the observed ultrasonic data based on the interaction of the ultrasound with cracks radiating from the damage site was tested using two-dimensional numerical simulations. The simulated results exhibit qualitatively similar characteristics to the experimental data and demonstrate the usefulness of numerical simulation as an aid for ultrasonic signal interpretation. The observed sensitivity to subsurface morphology makes the ultrasonic methodology a promising tool for monitoring laser damage in large aperture laser optics used in fusion energy research